SEATTLE -- Chris Taylor, last year's Mariners Minor League Player of the Year, arrived in Seattle on Thursday and found himself immediately penciled into the lineup as the starting shortstop on a team fighting for a playoff spot.

"I don't think I'd be alive if I didn't have a little butterflies," the 23-year-old said before his Major League debut in the series opener with the Orioles. "But that's what makes this game great. I couldn't be more excited."

Taylor and designated hitter Jesus Montero were called up from Triple-A Tacoma in time to start Thursday's game against the Orioles. Taylor was selected from Tacoma and added to the 40-man roster, while Montero was recalled for the second time this season.

Veteran utility man Willie Bloomquist was placed on the 15-day disabled list with a bruised right knee to open one spot on the 25-man roster, while the club already had another opening after optioning Taijuan Walker back to Tacoma following Wednesday's 3-2 loss to the Mets.

Montero's stay may be short as the club will need to make another roster move Friday with the arrival of designated hitter/first baseman Kendrys Morales, who was acquired by trade from the Twins on Thursday. But Taylor figures to be given a shot at shortstop, where general manager Jack Zduriencik said his right-handed bat is a key addition to a club with so many left-handed hitters.

"I guess overwhelmed is the biggest thing," Taylor said upon arriving at Safeco Field for the first time as a big leaguer. "I found out this morning and couldn't be more thrilled. It's a dream come true. And being able to call my parents, it was tough to hold it together. That moment is something you'll never forget. Talking to them on the phone and hearing their voices and how excited they were, it's just an indescribable feeling."

Taylor, ranked by MLB.com as the club's No. 8 prospect, was second in the Pacific Coast League with a .328 average and had 63 runs scored, 22 doubles, seven triples, five home runs and 37 RBIs in 75 games for Tacoma.

"You really have to tip your hat to this kid," said Zduriencik. "This was player of game at the Triple-A All-Star Game. What he did last year was terrific. He's a kid who deserves a chance right now. He has an opportunity to help us and gives us a window to see him."

Brad Miller beat out Nick Franklin for the starting shortstop job in Spring Training but has hit just .205 with eight home runs and 26 RBIs in 86 games. Miller has hit .261 in his last 33 games, but Zduriencik and manager Lloyd McClendon said Taylor will be given a chance to compete for playing time.

"Any time a guy is swinging well and you have an opportunity to bring 'em, you want them in the lineup," McClendon said. "You don't want him sitting, and hopefully it can continue up here. I would say he'll get his fair share of playing time."

"The whole infield is left-handed," Zduriencik said. "The fact he's right-handed was really a factor in this decision. He's a Triple-A All-Star, what he did last year was terrific and we'll see. Let the best man play."

Montero, 24, hit .286 (4-for-14) with one home run and two RBIs in five games in his previous stint with Seattle last month. He is batting .310 with 23 doubles, 15 home runs and 69 RBIs in 80 games with the Rainiers, including a .420 average with seven home runs and 29 RBIs in 21 games since being optioned back to Tacoma on June 25.

Zduriencik made no promises about Montero's long-term chances, given Morales' pending arrival, but he was in the lineup Thursday at DH and batting sixth.

Bloomquist, 36, was having an MRI on his knee Thursday after injuring himself running out an RBI grounder in the eighth inning in Wednesday's loss on a play where he originally was ruled safe, before the call was overturned on replay. In 47 games this season, he is batting .278 while playing seven different positions.

McClendon said both Taylor and Miller can play all the infield positions and whoever isn't in the lineup would fill Bloomquist's backup utility role.

With Taylor's addition, the 40-man roster is now at 39 players, with two pitchers -- Blake Beavan and James Paxton -- on the 60-day disabled list.